Machine tool way guard



March 18, 1947. J.,B. ARMnAGE 1 MACHINE TOOL YAY GUAR 2 Sheets-Sheet 1 Filed Aug. 2, 194s um wm. U mm mw.$...-. xm T a NM `w QN N\ -NN W m la N WA I S NNK a uw. .W\.\.. h MMI 8./ u. .VWM i. 3f n n. m o 4 e um n Q Mmwm www m n\\ Q 7 n i Q Q int MEE@ um. N\\ f ,f m \\\N\N\\I\\\\\\\\\\ w www L 1111 l a m\ .n\'\\ N. E

March 1s, 1947. J, B, ARMWAGE Y2,417,671

MAHINE TOOL wu GUARD Filed Aug. 2, 1943 2 Sheets-Sheet 2- INVENTOR JOSE HBARMITAGJE BY 4( t ATTORNEY Peamed Mu'. 1s,- 1941 UNITED sq'rArss I ATENT ori-*ics Y Application August 2, 19473, Serial No. 497,034

1s calms.v (ci. aos- 3.5)

'rms invention relates, generally; to improvements in way guards and more particularly' to an v improved way guard especially adapted to protect the bearing ways 'of a machine tool.

A general object of the invention is to provide an improved machine tool way guard. r Another object of the invention islto provide an improved compensating mechanism for way guards so arranged that one guard is made to retract while a second guard is made to advance along the way surface in accordance with movement of the carriage traveling thereon.

Another object of the invention is to provide i a way guard supporting means so arranged that chips and debris deposited on the top of the guard strip cannot be transferred to the opposite face of the guard and subsequently deposited on the way surfaces of the machine.

Another object ofthe invention is to provide 20 gitudinal vertical section taken substantially alongythe line I`4 in Fig. 2 and showing the a way guard retracting mechanism arranged to operably support the guard within the interior I of a machine structure without interfering with the driving mechanism therein. A

`A further object of this invention is to pro; vide a way guard mechanism having improved tensioning means for retaining the guard in a taut condition.

A still further object of the invention is to provide a way guard arranged to protect a plurality of paralleily disposed way surfaces.

According to this invention, the way surfaces of a machine tool are protected by means of `exlble guard strips arranged to be drawn onto `and retracted from the ways in accordance with movement of the traveling carriage. I As the guard strips are retracted, they are drawn into the ends of the machine bed-and looped around idler rollers therein in such manner that the sur- ,faces which pass over the ways are .protected from contaminatiom To effect the retracting action, the idler pulleys are arranged for movement within the bed. the pulleys at one end of the bed being connected tolthose at the other end by cables arranged in such manner that as the guard strips are paid out to follow the carriage along the ways, the cables exert forces upon the idler Pulleys at the other end of the bed to retract the associated guards from in front of the carriage. The ends of the guard strips are securedl by springs to maintain them under tensionandthepartsofthestripswithinthebed are looped armmd the idler pulleys in such man- .ner that debris falling from the upper inverted runs'of the strips'will drop uponthe top of the lower runs without coming in contact with the was surfaces.

'Ihe foregoing and other objects of this inven-` tion, which will become more fully apparent from the following detailed description, may be achieved by means of the exemplifying apparatus depicted in and set forth in this specification inconnection with the accompanying drawing,

in which: I Y

Figure 1 is a longitudinal vertical sectional view through the base of a milling machine showing the way guard mechanismarranged to protect the way surfaces for supporting the table; Fig. 2 is a top plan view partially in horizontal section showing the way guard mechanism and" its relationship to the machine base and table;

Fig. 3 is a vertical transverse sectional View taken substantially along the line 3-3 in Fig. 1 and showing the ways, way guards and guard retaining mechanism;

Fig. 4 is an 'enlarged fragmentary view in lonway guardmechanism in greater detail;

Fig. 5 is an enlarged view in transverse vertical section taken substantially along the line 5-5 2s in rig. 4 and snowing the dei-.aneamounung of strip serves to protect a plurality of parallelly disposed ways.

Referring morespeciilcally to the drawings, and particularly' to Figs'. 1 and.` 2 thereof con-V stituting general views of parts of a machine tool 35 embodying the present invention, it will be seen that the, machine structure there shown comprises essentially a relatively long base or bed III having two horizontally disposed parallel way surfaces Il'and I2 upon which is slidably sup- "40 ported a work tableor carriage I3. The table I3 may be moved horizontally along ,the way surfaces by means of a table screw Vand nut assem# bly Il that may be operated either manually or by power. As shown in Fig'. 1, the table screw is rotatably journalled in two end brackets I5 and I3 bolted to the right and left ends of the table I3 respectivelyand 'the nut is iixed to the base or bed Il. Relative rotation between the screw and the nut in effecting .power feeding move- 5o ment of the table is accomplished by driving the table screw in the usual-manner by means of a on drive mechanism v(notshown) located in a centralcompartment IT within the In machine "tool having way surfaces, the

ent upon the maintenance of the way surfaces in perfect condition without scratches or marks. The accumulation of chips and other debris on the way surfaces brings about damage to these surfaces since movement of the table causes chips to become wedged between the bed and the table I3 on the way surface and consequently causes scratches and ultimate Wearing away of the surfaces. The invention herein set forth presents an improved means for guarding the way surfaces of a machine tool.

As shown in Fig. 2, it is evident that when the carriage or table I3 is wholly supported on the parallel ways II and I2, there are ordinarily four portions of the ways which are exposed and upon which damaging foreign elements may collect. To afford protection to these four surfaces, the way guard mechanism embodying the present invention includes four flat or pre-formed strips or guard elements 20, 2|, 22 and 23,. one arranged to 'overlie each of the four exposed portionsof the two way surfaces |I and I2. Thus the guard 20 is disposed to cover the exposed left end of the way I2 while guard 2| serves to cover the exposed right end of the same way. Similarly, guard 22 is positioned to protect the exposed left end of way |I and guard 23 is positioned to protect the exposed right end of this way. The length of the exposed portion of any way surface at a given instant is, of course, dependent upon the position of the table. Thus, as shown in Figs. l and 2, when the table I3 is positioned at the extreme right end of the base lll, the maximum area of the way surfaces I| and I2 at the leftl end of the base will then b exposed while a minimum area of the same way surfaces will be exposed at the right end of the base.

One end of each of the way guards is fastened to the end of the table or carriage I3 directly over the respective way surface in position to lie longitudinally along the top of the surface it is to protect. The guard retaining and guiding mechanismsfor each of the four way guards 2l), 2|, 22 and 23 are similar in construction although differently arranged to assume different positions within the machine base l0. By way of example, the mechanism associated with the guard 2U protecting the left end of the Way surface I2, as shown in Fig. 4, includes a at-faced pulley or roller 25 rotatably mounted on a short shaft 26 which is carried in a frame or bracket member Z'I. The bracket 2'I is bolted to the vertical end wall of the base I Il in such manner that the top peripheral surface of the roller 25 is slightly 'above the way surface. The width of the roller 25 between its flanged edges is slightly greater than the width of the way strip or guard necessary to fully cover the w'ay. A shield 28 of generally arcuate shape is integrally formed with the frame member 21 and positioned to prevent accidental engagement with the rotating roller while permitting any debris deposited on the way guard 20 to pass through and drop from the guard as it moves downwardly over the periphery of the roller.

` An automatic compensating harness mechanism 30 is contained within the hollow interior of the base I0 to maintain the guards or strips taut regardless ofthe position'assumed by the carriage or table I3. This mechanism effects the retraction of the guard from the way surface in front of the advancing table and permits a corresponding advance of the complementary guard onto the way surface behind the advancing table. The harness mechanism 30 for the guard strip 20 for example includes a movable flanged pulley 3| mounted on a shaft 32 for rotation and for bodily movement in a horizontal plane longitudinally of the base parallel to and beneath the way surface I2.

Horizontal movement of the pulley 3| and shaft 32 occurs along a pair of channel shaped tracks 33 and 34,.as generally shown in Figs. 2 and 3. These tracks are parallelly disposed on the opposite inner faces of the vertical longitudinal walls of the base I0. The left or outer end of the track 33 is bolted to a. channel shaped block 35 integrally formed with a rectangular cover plate 36 which is bolted in a recess in the base I0 (see Figs. 4 and 5). 'I'he right or inner end of the track as seen in Figs. 1 and 4, is bolted to achannel shaped block 31 attached to a circular cover plate 38. The cover plate fits into a correspondingly shaped recess in the vertical wall of the base and is bolted thereto. The track 34 is mounted in the same manner on the opposite vertical walljof the base. The shaft 32 of the mechanism 30 is of sufficient length to t between the upright walls of the tracks 33 and 34 and to ride on the extending iianges of the said tracks. This is accomplished by means of a roller-bearing 39 (see Fig. 5) pressed on each end of the shaft 32 and presenting a steel rim 40 carried by the outer race of the bearing. Thus with each end of the shaft disposed to ride on its respective track, the shaft is restricted to travel in a horizontal plane parallel to the way surface I2.

The way guard 20, after passing half way around the pulley 25, leaves the bottom peripheralvsurface of the pulley and extends in reversed direction through an opening in the vertical end wall of the base il) and is looped back upon itself in manner to pass half Way around the pulley 3|. The other end of the guard is resiliently anchored on the frame member 2l, as shown in Figs. 1 and 4. For this purpose, the end of the guard is attached to a retaining plate 43 and a coil tension spring 44 is disposed between the plate 43 and an axially adjustable hook member 45 that extends through the end wall and serves to retain the entire length of the guard in a taut condition at all times, regardless of the position of the table I3 on the way surface I2. The hook member 45 is axially adjustable from the outside of the base in order to afford a convenient means for varying the degree of tautness or for compensating for any elongation of the guard which may occur after continued use.

Since the compensating harness mechanism 30 retaining the way guard 2| at the right end of the base, as shown in Fig. l, is similar to though oppositely arranged from the mechanism just described in connection with the guard 20, it becomes evident that a unified response from both mechanisms occurring upon any movement of the table or carriage I3 will effect compensating action upon both way guards 2U and 2|. The unified action of both mechanisms is made possible through an interconnecting flexible cable 48. `A sleeve bearing 49 (see Fig. 4) permits a flange member 50 to oat on the shaft 32 adjacent to the pulley 3| without rotating therewith. One end of the cable 48 is anchored to a clevis 5I which is pinned to the member 5I) associated with the mechanism 30 supporting way guard 20 while the other end of the cable is similarly fastened to a clevis 52 which is pinned to a flange member associated with the mechanism 30 supporting way guard 2|.

A sheave 53 mounted for free rotation within the base III carries the cable 48 and leads it downwardly to a sheave 54 likewise mounted for free rotation near the bottom of the base. The sheave compartment I1 serves to carry the cable 48 beneath the mechanism in the center compartment E?. Another sheave 56 carries the cable 48 for a corresponding horizontal connection with the mechanism 3@ in the right end of. the base. `Thus the way guard harness mechanisms till are individually disposed in the two ends of the basel without interfering with any of the table drive mechanism contained in the middle compartment. lt is evident that the force exerted upon either of the compensatory mechanisms 30 by the cable et effects a horizontal movement of the mechanism and retracting movement of the asscciated way guard.

"ihus referring again to Fig. 1, the complete cycle oi operation of the way guard mechanism is readily apparent. With the table I3 inthe extreme right hand position as shown, the way guard di is completely retracted, with the carrier shaft 32 and pulley 3l associated therewith positioned at the extreme innermost position on the tracks. The Way guard 2li is then fully extended upon the way surface with compensatory mechanism 3U associated therewith positioned at the extreme outermost station on the tracks. If it is assumed that power is applied to the table Vscrew and nut assembly it so as to eilect a table movement to the left, the guard 2t must be retracted and the guard 2l must be advanced on the way surface I2. As the table moves to the left. the guard 2i is drawn with thet tableonto the Way surface. 'The increased tension on the guard 2l causes a rightward movement of the movable shaft and pulley retaining the guard. This movement tends to relieve the tension on the guard and to impart tension to the cable 48.

The pulling force thus applied to the right end of the cable B is transmitted to the movablev shaft 32 and pulley 3i retaining the Wayguard 20. Thus the harness mechanism 30 is made to operate in a rightwardly direction and in doing so retracts the guard 2li from the way surface at the same rate of speedA as that of the table I3. Since the purpose of the coil spring M is to place a slight tension on the guard at all times, the guard will not buckle or bend during a retracting or advancing movement and consequently the guard cannot be damaged through excessive nexing. No matter where the table is stopped on the way surface, both guards will remain taut and under an even tension since the compensating mechanisms 30 retaining the guards are both retentatively positioned on the tracks in a given position until the table is again moved.

When the table I3 has reached the extreme lefthand position, as indicated by the dotted lines in Fig. 1, the tensioning mechanism 30 in the left end of the base I for the way guard 20 will be in an extreme innermost position' on the tracks, as indicated by the dotted lines, so that the guard will be completely withdrawn from the way surface I2. At the same time, the way guard 2| will be fully advanced on the exposed left end of the same way surface and the harness mechanism for thisl guard will then reach the extreme outermost position, as indicated by the dotted lines. Reversed movement of the table to the right will cause the initial tension to be placedV on the way guard 20 which in turn will effect a leftward movement lof the carrier pulley 3| and 6 shaft 32 associated therewith on the tracks. A correspondingmovement of the carrierpulley and shaft in the right end of the base I0 and associated with thev guard 2| will occur and accomplish a retraction of the guard 2i from the -way surface I2 in front of the advancing table i3.

Although the explanation of the operation of the way guard compensatory mechanism has been made With reference to the guards @d and parent from Fig, 2 that a'duplicate arrangement of the harness mechanism isprovided for, the guards 22 and 23 associated with the other way surface Il. As previously explained, the shafts 32 of the harness mechanism til for the two ends `oi the machine are supported at their ends in track-ways mounted on the respective inner walls of the base. As shown,` each shaft 32 carries a anged pulley 3l near each end and likewise carries a flange member 50 near each pulley, there being two cables d8 connected at their ends to the anges of each shaft and arrangediin spaced relationship Within the base. 'By this arrangement, both ends of the shafts 32 are arranged to be moved simultaneously by the two cables and both guard strips at each end of the machine are maintained Ain taut condition.

rI'he particular embodiment of the invention herein set forth has been shown in association with a typical machine tool structure having the usual pair of slide supporting ways, although it is to be understood that the protective apparatus may be modified readily to provide for protecting a single Way surface or any number of adjacent Way surfaces arranged in parallel relationship.

In Fig. 6 a modied version of the 'Way guard i invention is shown,` in which a single way guard or strip t5 is adapted to cover two or more way surfaces, the principle 0f operation being identical to that previously described. In this modification, a comparatively wide exible guard 65 is attached to the table bracket I5 on the end of the table I3, in manner to extend over both of the Way surfaces II and I2 on the base l0.. The guard 65 is operatively supported in alignment over the Way surfaces by a, flanged drum-type pulley 86 rotatably mounted in a bracket member 61 bolted on the vertical end wall of the base and extending the full width thereof. A wide shield 58 integrally cast with the member tl and generally similar to the narrow shields 28 shown in Fig; 2, serves as a ,protective means over the top of the guard E5 and pulley E6. Beneath the pulley E6, the way guard 65 extends into the interior of the base and over a wide faced, drumtype pulley 69 rotatably disposed on the shaft 32 that is arranged to travel along the pair of tracks 33 and 34, parallelly bolted Within the opposite o longitudinal sidewalls ofthe base, as previously described. ,The wide flexible guard 65 extends halfway around the pulley 69 and is fastened to the vertical endwall of the base by means of a series of coil springs T0. Thus the guard is retained under a'slight tension at all times. A second flexible guard (not shown) is likewise fastened to the other end ofthe table I3 and operatively mounted for compensating movement over the same way surfaces in a manner identical to that previously. described. Since a single wide pulley 69 was used to support the full width of `the guard Within the base, the ange members 50 are now positionedintermediate the 'ends of the pulley 69 and the rims 40 rotatably mounted to ride on their respective tracks 33 and 34. Like- 2|- protecting the Way surface I2, it will he an Y pended thereunder.

wise, the two cables Il, only one" of which is shown in Fig. 6, and their supporting sheaves areshifted to a position alongside the longitudinal sidewalls of the base. As the table Il advances to the right, a pulling force applied to the cables 4B by the movement of the second guard harness mechanism in the left end of the base will effect a leftward movement of the pulley` 69 and consequently cause a retraction of the guard 65 from -the way surfaces in front of the advancing table.

If the table i3 is moved to the left, it draws the way guard 65 onto the way surfaces and in doing so, the pulley assembly Il is forced to move toward the right end of the base. This movement results in the transmission of a pulling force through the cables I8 to the guard retaining mechanism within the left end of the base, as previously explained. and in the retractive movement of the guard from the way surfaces at the other end' of the base.

An important feature of this invention lies in the fact that chips and other debris deposited on the top surface of the Way guard cannot be transferred to the bottom surface of the guard and thence to the way surface, since if this should occur, the entire purpose of the guard would be defeated. With the present arrangement, the greater partof the d-ust, chips and debris which are deposited on the top surface of the guard strip will fall off the guard as it is retracted over the roller 2'5 at the .end of the base. Even if the top surface of the guard is oily and the foreign particles deposited thereon adhere to it and fail to drop off, they will not be transmitted to the other sideof the guard. As the guard is withdrawn into the base after leaving vthe roller 25, it is retained in a horizontal inverted position and if the oily chips or dust particles drop away from the guard while it is in an inverted position, they willmerely fall onto the top surface of the portion of the guard horizontally sus- With this arrangement of the guard, the bottom-face thereof which extends above the way surface never is exposed to chips, debris or dust particles.

This invention is applicable to any type of machine way, various minor constructional changes being necessary in order to adapt the invention to various types of horizontally or vertically disposed way surfaces. It is also evident that this invention is applicable to a machine 1 vtool base having only a single way and equally as well as a machine having a plurality of ways.

The aforedescribed invention is herein shown as applied to protect the ways of a large bed type milling machine. However, itv is to be understood-that this particular embodiment of the invention is intended to be illustrative only and that various other embodiments, all within the scope of equivalents of the characteristics defined in the subjoined claims. may be utilized by those skilled in the art in practicing various features of the invention without departing from its spirit.

'I'he ,principles of the invention having now been fully explained in connection with the exemplifylng apparatus herein set forth, I hereby claim as my invention and discovery:

1. In a machine tool, a base presenting a horizontally disposed bearing way, a carriage slid- .ably mounted for movement along said bearing way, a guard for said bearing way comprising a flexible strip of protective material attached at one end to said carriage and disposed to overlie said` bearing way, guide means on said base at the end of said way arranged to guide said guard strip into the end of vsaid base in inverted position, an idler pulley movably mounted within said base beneath said way and disposed to receive and reverse said guard strip, resilient means arranged to attach the reversed end of said guard strip to the end of said base, and means disposed to exert force upon said idler pulley to maintain said guard strip taut and to provide forv retracting or paying out said strip in accordance with movement of said carriage along said way while protecting the way engaging surface of said strip from contamination.

2. In a machine tool, the combination with a frame presenting parallel ways and a carriage slidably mounted on said ways, of way guard mechanism including a guide pulley mounted at each end of each way, flexible protective strips connected to said carriage and extending therefrom along said ways and over said guide pulleys said strips being looped within said frame beneath said ways, resilient means arranged to connect the looped ends of said strips to said frame, movable idler pulleys disposed within the loops of said strips within said frame, and motion transmitting means interconnecting said movable idler pulleys in manner to maintain tension upon said strips while permitting movement thereof in accordance with movement of said carriage.

3. In a machine tool structure, a frame presenting bearing ways, a carriage slidably mounted on said bearing ways for reciprocatory movement therealong, a roller mounted on said frame at each end of said bearing ways, an'idler pulley mounted for bodily movement within said frame beneath said ways at each end thereof, a flexible protective strip associated with each end of said ways said strips each being fastened at one end to said frame looped around the corresponding bodily movable idler pulley in extended condition passed over the corresponding end roller and along the surface of said Way and then fastened at its other end to said carriage, and means exerting force upon said movably mounted idler pulleys for moving them bodily to maintain said protective strips in extended taut condition while permitting play thereof around said. pulleys and rollers in accommodatingmovement of said carriage along said ways.

4. In a machine tool having a frame presenting ways upo n which a movable carriage is slidably mounted, means for protecting one of said ways comprising a exible strip attached to said carriage directly above said way and arranged to extend along said way, a pulley rotatably attached to said frame and positioned at the end of said way to deflect said strip therefrom, a movably mounted harness mechanism operably disposed to retain said strip in an extended po- I sition within said frame, tensioning means attached to the other end of said strip to retain said strip taut at all times, a secondstrip attached to the other end of said carriage to extend along and protect said way surface said strip being deflected therefrom in a similar manner, a second movably mounted harness mechanism operably disposed to retain said second strip in an extended position within said frame, motion transmitting mechanism interconnecting said harness mechanisms for moving them bodily in unified operation, and a second tensioning means operatively connected to retain said second strip taut, whereby one of said strips is advanced while the vother of said strips is retracted from said way gemert A depending upon the direction of .travel of said carriage on said ways.

5. In a machine tool, the combination with a frame presentingways and a carriagel slidably mounted on'said ways, of means for guarding said ways comprising strips of ilexible protective material secured to said carriage and extending therefrom along said ways throughout their length, rollers at the ends of said ways disposed to receive said guard strips and guide them into said frame beneath said ways; idler rollers mount-i ed for bodily movement within said frame in position to receive loops of said strips in extended condition, means securing the ends of said strips to said frame; and means exerting force on said idler rollers fori'noving them bodily to 'maintain tension in said guard strips while holding them extended Within said frame, whereby said strips may be caused to move over said ways in accordance with movement of said carriage While maintained under predetermined tension.

6. A Way guard reciprocating mechanism adapt/able to a machine tool having a `base withv Ways thereon and a carriage slidably mounted on said ways comprising a pair of ilexible strips adapted to protect said Ways and fastened on each engl of said carriage, guide rollers mounted on said base adjacent each end of said ways over which said strips pass iinto said base, tracks disposed parallel to said vlays Within said base, re-

" taining iframes mounted on said tracks, interconnecting means between said frames to e'ect an equally tensioned converse movement ci said strips, intermediate rollers rotatably mounted in said frames to carry said strips, and resilient clamps to fasten the other ends of said strips within said base. Y

'7. In a machine` tool with a base having way surfaces upon which a traveling carriage is slidably mounted, a guard mechanism for said way surfaces lcomprising a way guard for each exposed way surface on both ends of said carriage,

a pulley rotatably mounted on said base at each end of said surfaces to operably support said guard. a bodily movable harness mechanism operablv disposed to engage the guards on one end of said carriage and mounted Within one end of said base, a second bodily movable harness mechanism operably disposedto engage the guards on the other end of said carriage and mounted within the other end of said base, 'and cable means interconnecting vsaid harness mechanisms Aand serving to move them bodily in unison to provide for advancement of said guards at one end of said carriage and retraction of said guards at the other end of said carriage at a rate in accordance with the feed rateiof said carriage while maintaining them in extended taut condition.

8. In a machine tool4 having a base presenting a way surface and a carriage movably mounted on said way surface, a ilexibleway guard at4 within each end of said base in position to engageand retain said guards in extended taut condition and operatively interconnected to provide for unitary bodily movement to eiect advancel ment or retraction of the said guards as said carriage travels on said way surfaces. l9. In a machine tool .having a frame'presenting a multiplicity of ways upon which a movable carriage is slidably mounted, means for protecting said Ways comprising a pair oi.suiilciently wide iiexible way guards to cover all of said ways andeach operably attachedto opposite ends of said carriage for unified movement therewith,

a pair of pulleys rotatably mounted adjacent to the ends of said ways to operably support said guards, a bodily movable compensating harness means operatively engaging each of said guards,

mechanism interconnecting said'harness means' in manner to provide for compensated advancement or retraction of said guards on said ways in accordance with movement of said carriage and resilient anchoring means for said guards, whereby said guards are constantly retained in extended taut position to render the way engagy ing face thereof and the way free of dust, chips or other foreign matter.

l0. A way guard reciprocating mechanism applicable to any machine having way surfaces an'd a traveling ycarriage thereon comprising a pair of flexible .Way guards longitudinally disposed to overlie said Way with one end Aof each'guard hiredly attachedto opposite ends of said carriage, a guide means at each end of said way disposed to deect said guard from said way surface, a'

pair of tracks parallelly `disposed to said way, a

compensating harness mechanism operably mounted on each of said'tracks and serving as ientl means to secure the other end of said guards and interconnectingmotion transmitting means between said harness mechanisms for eiecting cooperative action thereof,` whereby said guards are advanced on or retracted from said way surfaces in accordance with movements of said carriage.`

11. In 'a way guardsystem for protecting a machine tool way, a strip of flexible protective material disposed to overlie the way and to be movable therealong in accordance with the movement of a machine element along said way, a, pulley at the end of said way disposed to receive said protective strip and guide a portion of it beneath said way. a movable ider pulley disposed to engage a loop of said strip beneath said Way, resilient means arranged to secure the end oi said strip, and means to exert `force upon said movable idler pulley to take up slack in said strip to compensate for movement thereof along said way.

12. In a machine tool, the combination with a frame presenting bearing ways and a carriage slidably mounted on said ways, oi! a way guard system comprising a strip of flexible protective material extending in each directionfrom said carriage along said ways. a guide at each end of said ways disposed to receive said strip and to guide it into said frame beneath said ways, means securing the ends of said strips to said frame, bodily' movable idler rollers engaging loops in said strips beneath said ways in manner tb maintain said strips extended, and means interconnecting said idler rollers in manner to provide for complementary movement thereof to maintain tension in said strips.

. 13. In a machine tool comprising a base-presenting slide ways and a carriage slidably mounted on said ways, means to protect said ways from in manner providing slack for permitting full movement of said carriage, and an interconnected bodily movable idler pulley compensating arrangement cooperating with said bands in manner to take up and pay out the slack in said bands while maintaining them in extended taut condition with the way contacting surfaces thereof free from contamination by foreign matter.s

14. In a machine tool, a base provided with slide ways, a carriage slidably mounted on said ways for reciprocating movement therealong, means to protect said ways from damage including a flexible strip overlying each exposed portion of said ways, means connecting one endl of each strip to said carriage for lmovement with it, an idler wheel rotatably mounted on said base at each end of each slide way for receiving the way engaging surface of each of said strips, an

- idler wheel rotatably and movably mounted for bodily movement beneath each of said ways for receiving the back oi' each of said strips, means securing the ends of said strips to said base, and meansl interconnecting said movably mounted idler wheels for bodily movement in unison in manner to provide for maintaining said strips' in extended taut condition and paying out'said strips at one end of said base while taking in said strips at the other end of said base, the arrangement being such that the way engaging surfaces of said strips are protected from contamination by foreign matter.

15. In a machine, tool, the combination with a frame presenting parallel ways and a carriage slidably mounted on said ways,of guard mechanism' for said ways including a guide pulley rotatably mounted at each end of each way, flexible protective strips each connected at one end to said carriage and extending therefrom along said ways and over saidguide pulleys, said strips being looped within said frame beneath said ways,

4ed at each end of 'each 12 resilient means arranged 'to connect the other end of each of said strips to said frame. bodily movable idler pulleys engaging and supprtins the loops of said strips within said frame, and motion transmitting means interconnectingl said bodily movable idler pulleys for cooperative ac-v tion in manner to maintain tension upon said strips while permitting movement thereof in accordance with movement of said carriage.

16. In a machine tool having a hollow frame presenting bearing ways and a carriage slidably mounted on said ways, guard mechanism for said ways comprising a guide pulley rotatably mountyay, a ilexible protective strip extending over each end of each way and connected at one end to said carriage,said strips running over said pulleys and being looped within said hollow frame, means connecting the other end of each looped strip to said frame, a. pulley engaged within the loop of each strip and movably mounted within said frame, and motion transmitting vmechanism interconnecting the movable pulleys within one end of said frame with those within the other end thereof in manner to exert force between them for maintaining said strips taut while permitting movement of said pulleys to take in and pay out said strips alternately in accordance with movements of said carriage along said ways.

JOSEPH B. ARMITAGE.

REFERENCES CITED The following references are of record in the iileof this patent:

UNITED STATES PATENTS Number Name v Date 2,246,199 Caldwell June 17, 1941 1,937,985 Schnuck Dec. 5, 1933 1,895,122 Benedict Jan. 24, 1933 1,679,912 Mondlock Aug. 7, 1928 2,033,141 Kraut et al. Mai. 10, 1936 848,578 Thelin Mar. 26, 1907 2,190,213 .Meyer Feb. 13, 1940 

